JPH06190835A - Production of silicone rubber molded piece - Google Patents

Abstract

PURPOSE:To ensure a stable and efficient production by a method wherein a silicone film is previously formed on a predetermined part of a mold, a plate, or a carrier sheet before molding. CONSTITUTION:A silicone film 1 is provided on a surface of a lower mold 4. A fluororesin releasant layer 2 is provided on a surface of an upper mold 3. When the molds are opened after molding, a molded piece adheres to the lower mold 4 through the silicone film 1, but can be easily released from the lower mold with the silicone film 1 remaining on the surface of the lower mold 4. In this manner, since the molded piece can be always bonded to a predetermined position of the mold or the like when the molds are opened in the molding of a silicone rubber, a stable and efficient production can be ensured. In addition, since the components of the silicone film are identical or similar to those of the molded piece, the function of the molded piece is not affected by the silicone film if by any chance it should adhere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silicone rubber molded article, which ensures that the molded article is always brought into close contact with a fixed position at a fixed position after completion of the molding so that the molded article can be released from the mold stably. This makes the process more efficient and can be used in the manufacture of various molded products, and is extremely useful for automatic removal of molded products.

[0002]

2. Description of the Related Art Conventionally, silicone rubber moldings have been manufactured by molding methods such as compression molding, injection molding, transfer molding and extrusion molding. In many cases of those manufacturing methods, the cavity of the mold is filled with unvulcanized raw material in which a silicone rubber compound, a cross-linking agent, a pigment, an additive, etc. are mixed, and between the plates or between the plate and the carrier sheet. The unvulcanized raw material is filled in a space such as a space, and the molding temperature and molding time corresponding to the filling amount and the shape of the molded product,
Molding is performed under molding conditions unique to each molding method. After the molding time has elapsed, the mold is opened and the molded product is released from the mold by a hand or a robot. At that time, if the mold, plate, carrier sheet, etc. that come into contact with the unvulcanized raw material are not subjected to surface treatment in advance, the molded product will be in contact with the molded product when the mold is opened, for example, when molding with the mold. It has a large area and tends to stick to the mold on the side where the cavity is deeply engraved, and when the unvulcanized raw material is sandwiched between the plate and the plate or the plate and the carrier sheet, it sticks to the one with a rough surface. Tend to do. However, since these phenomena are not reproducible, they reduce work efficiency.

For this reason, conventionally, a fluororesin-based or surfactant-based release agent is applied to a surface which is not desired to be adhered, or in the case of a mold or the like, various types such as a fluororesin-based release agent are used. Applying a molded product to the specified surface as much as possible by applying plating with excellent mold releasability or making a large difference in surface roughness between the surface to which the molded product is to be adhered and the surface to which it is not desired to be adhered by blasting etc. Was doing.

[0004]

However, a release agent such as a surfactant may not provide sufficient releasability, and the difference in adhesiveness between the coated surface and the non-coated surface may not be sufficient. Although a system-based release agent exhibits sufficient performance in terms of releasability, it cannot be maintained because it is easily removed from the coated surface itself, and the fluororesin-based release agent migrates to the molded product. There is also a possibility that the adhesion of ink and paint may be deteriorated during printing and painting on the molded product in the later step. In addition, since the fluororesin-based plating material is soft, the plating layer tends to peel off during repeated molding, and the fluororesin also peels off when the mold is washed with alkali due to surface stains. Releasability is reduced. Further, it is desirable to avoid changing the surface roughness because it may greatly affect both the design and the function of the product, and it is disadvantageous because the processing cost becomes high.

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that in order to properly attach a molded product to a surface of a mold or the like to be closely adhered, a molded product should be adhered to that portion. The present invention has been accomplished by finding that it is sufficient to form a silicone-based film in advance. That is, the gist of the present invention resides in a method for producing a silicone rubber molded article, which comprises forming a silicone-based film on a predetermined portion of a mold, a plate or a carrier sheet in advance and then performing the molding.

The present invention will be described in detail below. A molded product having irregularities is usually molded by a mold composed of two or more sheets.In the method of the present invention, spraying or baking is performed on the mold surface to which the molded product is to be adhered before molding. To form a silicone film. When molding a sheet-like material, a silicone-based film is similarly formed on the surface of the plate or carrier sheet to be adhered in the same manner.

Any liquid material containing a silicone component may be used to form the silicone film, and a typical example is a silicone release agent.
Examples include silicone water repellents, silicone waterproof coating agents, silane coupling agents, silicone resins, silicone varnishes and silicone oils.

Of the above, specific examples of the silicone type release agent include oil type KF96, 410, 412 (above,
Shin-Etsu Chemical Co., Ltd., trade name), SH200, 70
90, 203, SF8416 (above, manufactured by Torre Dow Corning Co., Ltd., trade name), TSF451, 442
0, 4600, TSM620, 621 (above, product name of Toshiba Silicone Co., Ltd.), paste type KS61,
62F (above, Shin-Etsu Chemical Co., Ltd., trade name), S
H7071, 7072, SC7077 (above, Torre ・
Solution type KS7 manufactured by Dow Corning Co., Ltd.
02, 707, 717, 725 (above, Shin-Etsu Chemical Co., Ltd., trade name), SH237, PRX305, SH
7020, SRX202M, SR620PG (all manufactured by Torre Dow Corning, trade name), baking type KS700, 701, 737 (all manufactured by Shin-Etsu Chemical Co., Ltd., trade name), emulsion type KM722,
740, 742, 753, 780, 782, 785, 7
86, 787, 788, 797, 860, 2002, Silcast, water-soluble KM244 (above, Shin-Etsu Chemical Co., Ltd., trade name) and the like.

For the spray type, for example, KF96SP, K
F412SP, Release, Sepacoat H (above, Shin-Etsu Chemical Co., Ltd., trade name), SH200 Spray, Lilies (above, Tore Dow Corning Co., Ltd.,
(Trade name), TSM6801, 6811, YGS600
7, TSM6821, 6822, 6851, 6852
(These are products of Toshiba Silicone Co., Ltd., etc.), which can be easily applied.

The molded article seems to be tacky to the formed silicone-based film, which allows the molded article to adhere to the surface on which this film is formed via the silicone film. However, the adhesion is moderately strong and does not hinder the release of the molded product. If it is desired to more firmly adhere the molded product to the surface of the predetermined mold, plate, or carrier sheet, it is a conventionally known method. A method such as applying a release agent or baking a fluororesin-based plating may be used together.

An application example of the silicone-based film in the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view for explaining an application example of a silicone-based coating, and a lower mold 4
The silicone-based coating 1 is provided on the surface of the above, and the fluororesin-based release agent layer 2 is provided on the surface of the upper mold 3. In this case, when the mold is opened after molding, the molded product adheres to the lower mold 4 through the silicone-based film 1, but the silicone-based film 1 remains on the surface of the lower mold 4 and can be easily released. it can.

FIG. 2 is a cross-sectional view for explaining another application example of the silicone-based coating. The silicone-based coating 5 is provided on the surface of the carrier sheet 6, and the fluororesin-plated layer is provided on the surface of the upper plate 8. 7 is provided. Also in this case, the molded product adheres to the carrier sheet 6 through the silicone-based coating 5, but the silicone-based coating 5 can be left on the surface of the carrier sheet 6 and easily released.

3 and 4 show a conventional method corresponding to FIGS. 1 and 2, respectively, in which a silicone-based film is not provided. The effect of the fluororesin-based release agent or the fluororesin-plated layer may be reduced, and the molded product may adhere to the upper mold or the upper plate.

[0014]

【Example】

Example 1 In the production of a cover member for a push button switch made of silicone rubber, a silicone-based release agent, Sepacoat H (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) is applied to the surface on which the molded product is to be adhered with a two-piece mold. The surface of the molded product which has not been adhered to the molded product by baking is sprayed once every 5 shots with a fluororesin-based mold release agent, mold spat (product name, manufactured by Asahi Glass Co., Ltd.), and 1000 consecutive shots are injected by an injection molding machine ( It was performed by Nissei Jushi Kogyo Co., Ltd., but the molded product adhered to the surface to be adhered on all shots without exception.

[0015]

According to the present invention, when the mold is opened in the molding of silicone rubber, the molded product can be always brought into close contact with a predetermined position such as a mold, so that stable and efficient manufacturing can be achieved. became. Further, since the silicone-based film has the same or similar components as the molded product, even if it adheres to the molded product, it does not affect its function.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining an application example of a silicone-based film.

FIG. 2 is a cross-sectional view for explaining an application example of a silicone-based film.

FIG. 3 is an explanatory diagram of a cross section for explaining an example of a conventional method.

FIG. 4 is an explanatory diagram of a cross section for explaining an example of a conventional method.

[Explanation of symbols]

 1,5 Silicone type film 2,10 Fluororesin type release agent layer 3 Upper die 4 Lower die 6 Carrier sheet 7,11 Fluorine resin type plating layer 8 Upper plate 9 Lower plate

Claims (1)

[Claims] 1. A method for producing a silicone rubber molded article, which comprises forming a silicone-based film on a predetermined portion of a mold, a plate or a carrier sheet in advance and then performing molding.